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Al–Si-based alloys are widely used in the automobile and aerospace industries, whereas high entropy alloys have emerged with many attractive properties. In this study, AlCoCrFeNi high entropy alloy (HEA) is employed to improve the properties of AlSi10Mg alloy through a metal matrix composite approach. Metal matrix composite powder mixture was sintered at 500°C using a hot press at a pressure of 50 MPa. HEA phase was found to be distributed uniformly. An increase of 20 and 40% in hardness and compressive strength were observed by reinforcing HEA in AlSi10Mg alloy. [ABSTRACT FROM AUTHOR]

The frictional properties between the continuous hot pressing machine board, steel strip, steel strip, and hot press plate, as well as steel strip and sealing strip, were investigated in this paper. Friction coefficient tests were conducted using a friction coefficient tester to determine the friction coefficients between wood materials and polyethylene plastic, steel strip, polytetrafluoroethylene, polyethylene engineering plastic, and steel strip. Factors influencing the friction coefficients of various friction pairs were analyzed with the aim of providing reference for the design and manufacturing of the continuous hot press for laminating artificial boards with pressure air-float veneers. The experimental results indicated that the static friction coefficient between polytetrafluoroethylene and steel at room temperature was 0.10, and the dynamic friction coefficient was 0.01. The static friction coefficient between polytetrafluoroethylene plate and steel plate decreased initially and then increased with the increasing of temperature, while the dynamic friction coefficient continued to increase. In the direction perpendicular to the wood grain, the static friction coefficient was maximum when moving along the polyethylene plastic film, with the value of 0.62. In the friction pair of artificial board and polyethylene plastic, the static friction coefficient of mediumdensity fiberboard ranged between 0.61 and 0.69, while that of particleboard ranged between 0.56 and 0.71. [ABSTRACT FROM AUTHOR]

Copper and its alloys are widely used in the preparation of metal matrix composites due to their thermal and electrical conductivity. This study aims to improve the mechanical, tribological and electrical conductivity properties of copper (Cu) matrix powders by adding certain amounts (10 wt%) of reduced graphene oxide (rGO) nanopowder, boron (B), nitrogen (N) and silicon (Si) reinforced rGO nanopowder. Hybrid composites were produced by powder metallurgy production methods. The samples were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX) and Fourier‐transform infrared spectroscopy (FT‐IR) analysis for reinforcement, homogeneity and phase identification. The mechanical and tribological properties of the hybrid composites were investigated by hardness, wear tests and temperature dependent electrical conductivity tests to determine the effect of the reinforcement materials on the Cu matrix structure. The maximum hardness value was obtained from the (Cu–rGO–Si–B–N) hybrid composite with an increase of 193% compared to the pure Cu sample. When the coefficient of friction values of RGO and reinforced rGO hybrid composites were examined, a 219.12% lower coefficient of friction value was observed in the (Cu–rGO–Si–B–N) sample compared to the pure Cu sample. The highest value was observed in the temperature dependent electrical resistance analysis in the rGO reinforced sample. [ABSTRACT FROM AUTHOR]

Boron carbide (B4C) is an essential material in various high-performance applications due to its light weight and hardness. In this work, B4C-based composites were fabricated via a powder route consisting of powder mixing, precursor preparation, and hot-pressing under vacuum. The composites' mechanical properties and microstructure were analyzed to investigate the effect of adding minor second-phase particles. In addition to homogenizing the grain size, the addition of SiC (≤10 wt%) to B4C increased its strength and improved its fracture toughness, with values reaching 551 MPa and 3.22 MPa m1/2, respectively. Meanwhile, the addition of TiB2 (≤10 wt%) significantly improved the strength and fracture toughness only, with values reaching 548 MPa and 3.92 MPa m1/2, respectively, with only a minimal decrease in hardness. Microstructural analysis revealed that the second-phase particles were uniformly distributed and reduced the average grain size, contributing to the increase in strength. Additionally, the TiB2 particles impeded crack propagation and induced crack deflection at the interface, indicating the formation of an intergranular fracture mode. On the contrary, the addition of SiC primarily resulted in transgranular fracture behavior, though it still improved the toughness of the B4C. These results suggest that small amounts of SiC and TiB2 can effectively enhance the mechanical properties of B4C ceramics while maintaining the lightweight characteristics critical for military and aerospace applications. [ABSTRACT FROM AUTHOR]

Even though BiFeO3–BaTiO3 (BF–BT) with high Curie temperature and excellent piezoelectric properties is very suitable for high‐temperature applications, its rapid reduction in resistivity with temperature limits its further application. So far, there is no effective method to improve the resistivity of BF–BT at a high‐temperature state. In this work, hot‐press sintering combined with an oxygen atmosphere was used to prepare (1 − x)BF–xBT (x = 0.2–0.33) ceramics for the first time, which reduced the sintering temperature from 1000 to 920°C. The controllable grain size can be achieved by adjusting the sintering temperature and the applied pressure. The X‐ray photoelectron spectroscopy results confirmed that using hot‐press sintering effectively avoided the generation of heterovalent Fe ions, and the resistivity of BF–BT ceramics at the high‐temperature stage was improved by two orders of magnitude. It was found that hot‐press sintering can cause the oriented growth of the sample along the (1 1 0) direction, and further refined X‐ray diffraction was used to accurately analyze the changes in the lattice structure. The hot‐press sintered samples obtained larger polarization strength, especially the electro‐induced strain showed excellent temperature stability in the wide temperature range of 30–170°C. Hot‐pressing sintering combined with an oxygen atmosphere is more suitable for preparing high insulation and electrical breakdown resistance ceramics. [ABSTRACT FROM AUTHOR]

In this study, Its the influence of according to press, particleboards produced in two different press types which were multiday and continuous hot press, the thickness, density, bending strength, modulus of elasticity, internal bond, surface soundness, withdrawal of screw resistance, moisture, thickness swelling, water absorption, formaldehyde emission content were researched. 18 mm x 2100 mm x 2800 mm size particleboards were manufactured on the production line which was using urea-formaldehyde (F:U;1,07 moles), and 30 % pine, 40 % oak, 20 % beech and 10 % poplar waste mixture of the wood materials. According to results of the tests performed after the multiday and continuous hot press production of the boards; thickness (0,63 %), bending strength (1,27 %), moisture content (0,47 %), thickness swelling (37 %), and water absorption (39,9 %), modulus of elasticity (11,35 %), internal bond (7,22 %) were increased according to multiday hot press while density (2,7 %), surface soundness (18,81 %), withdrawal of screw resistance (14 %) and formaldehyde (57,12 %) decreased. Formaldehyde content, surface soundness, withdrawal of screw resistance are the most prominent properties influenced by continuous hot press. [ABSTRACT FROM AUTHOR]

In this paper, the effects of hot pressing and cold pressing on the superconducting properties of pyrene (C16H10) added bulk MgB2 were compared. For this aim, the polycrystalline disk-shaped MgB2 samples with addition of 4 wt % C16H10 powder were fabricated by a pellet/closed tube method at 850 °C, after hot pressing at 200 °C and cold pressing. The XRD and SEM results showed that although a-lattice parameters reduce for both C16H10 added samples, the average crystallite size increases after cold pressing because of the accumulation and inhomogeneous distribution of C in the MgB2 structure while it reduces for the C16H10 added hot pressed sample. The resistivity measurements showed that the increment of electron scattering is higher for the C16H10 added cold pressed sample than that of the C16H10 added hot pressed one which shows relatively better grain connectivity, and the Tc values of the samples are not appreciably affected by the pressing conditions. From the magnetisation measurements the in-field Jc values at 10 K and 5.5 T were obtained as 8.41 × 103 A/cm2, 1.62 × 104 A/cm2, 6.90 × 103 A/cm2 and the Hirr values while Jc = 100 A/cm2 at 20 K were obtained as 5.99 T, 6.55 T and 6.19 T for the pure sample and the C16H10 added hot and cold pressed samples, respectively. The higher Jc and Hirr values obtained for the C16H10 added hot pressed sample is because of the homogenous C substitution into MgB2 grains, as compatible with its lower Δρ value, and thus increased flux pinning ability. [ABSTRACT FROM AUTHOR]

Scanning Electron Microscope (SEM) is a crucial tool for studying microstructures of ceramic materials. However, the current practice heavily relies on manual efforts to extract porosity from SEM images. To address this issue, we propose PSTNet (Pyramid Segmentation Transformer Net) for grain and pore segmentation in SEM images, which merges multi-scale feature maps through operations like recombination and upsampling to predict and generate segmentation maps. These maps are used to predict the corresponding porosity at ceramic grain boundaries. To increase segmentation accuracy and minimize loss, we employ several strategies. (1) We train the micro-pore detection and segmentation model using publicly available Al2O3 and custom Y2O3 ceramic SEM images. We calculate the pixel percentage of segmented pores in SEM images to determine the surface porosity at the corresponding locations. (2) Utilizing high-temperature hot pressing sintering, we prepared and captured scanning electron microscope images of Y2O3 ceramics, with which a Y2O3 ceramic dataset was constructed through preprocessing and annotation. (3) We employed segmentation penalty cross-entropy loss, smooth L1 loss, and structural similarity (SSIM) loss as the constituent terms of a joint loss function. The segmentation penalty cross-entropy loss helps suppress segmentation loss bias, smooth L1 loss is utilized to reduce noise in images, and incorporating structural similarity into the loss function computation guides the model to better learn structural features of images, significantly improving the accuracy and robustness of semantic segmentation. (4) In the decoder stage, we utilized an improved version of the multi-head attention mechanism (MHA) for feature fusion, leading to a significant enhancement in model performance. Our model training is based on publicly available laser-sintered Al2O3 ceramic datasets and self-made high-temperature hot-pressed sintered Y2O3 ceramic datasets, and validation has been completed. Our Pix Acc score improves over the baseline by 12.2%, 86.52 vs. 76.01, and the mIoU score improves from by 25.5%, 69.10 vs. 51.49. The average relative errors on datasets Y2O3 and Al2O3 were 6.9% and 6.36%, respectively. [ABSTRACT FROM AUTHOR]

The anisotropic material behavior of continuous-fiber-reinforced composites that is evident in their mechanical properties should also be considered in their processing. An important step in the processing of thermoplastic unidirectional (UD) fiber-reinforced tapes is consolidation, where a layup consisting of locally welded UD tape layers is firmly bonded. Compression of the molten thermoplastic matrix material during consolidation leads to a squeeze flow, the direction of which is determined by the fibers. This work presents a model that describes the influence of fiber direction on compression and flow behavior, implemented in the computational fluid dynamics (CFD) software tool OpenFOAM®. To validate the simulation results, we performed experiments in a laboratory consolidation unit, capturing the squeeze flow with cameras and then quantifying it by gray-scale analysis. The specimens used were UD polycarbonate tapes (44% carbon fibers by volume) of various sizes and with various fiber directions. The simulation allows prediction of the changes in specimen geometry during consolidation and is a first step towards optimizing the process by avoiding extensive squeeze flow. [ABSTRACT FROM AUTHOR]

In this study, wet ball milling and hot press methods were used to prepare nanocomposite from ultra-high molecular weight polyethylene (UHMWPE) as a matrix, and modified multi wall carbon nanotubes (MWCNTs) as reinforcement nano-additives. Two batches of MWCNTs were used (Pristine-MWCNTs-B1, and Pristine-MWCNTs-B2). First, the MWCNTs were oxidized (oxide-MWCNTs) by wet chemistry using strong acids, then further functionalized with an amide group (A-MWCNTs). Fourier-transform infrared spectroscopy (FTIR), and Thermal gravimetric analysis (TGA) results confirm the functionalization of the MWCNT with the amide group. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to examine the surface morphology and crystalline behavior of MWCNT after functionalization. Ball milling was used to mix the UHMWPE with pristine MWCNT (1.5% wt), Oxide-MWCNT (1.5% wt), and A-MWCNTs (0.5–2% wt). Then, hot press melting was used to prepare the nanocomposite sheets. Fourier transform infrared spectroscopy (FTIR) confirmed the impact of the balls milling process with time factor on UHMWPE crystallinity and the interaction of the functionalization MWCNT with the UHMWPE matrix. The structure (crystallinity, crystal size) was validated using X-ray diffraction (XRD) patterns. Thermal gravimetric analysis (TGA), differential scanning calorimeter (DSC), and universal testing machine (UTM) were utilized to analyze the structural, thermal, and mechanical properties of the nanocomposites, respectively. The results showed that UHMWPE crystallinity increased after 2 h of ball milling, while crystallinity decreased when pristine-MWCNT, oxide-MWCNTs, and A-MWCNTs (0.5–2 wt%) were added without affecting the crystal structure of UHMWPE. The results showed that adding 1.5 wt% A-MWCNTs-(B1, B2)/UHMWPE increased thermal stability by 16 °C and elongation at the break by up to 74% when used 1.5 wt% A-MWCNT-B1 and 2 wt% A-MWCNT-B2. This shows that the ball milling methods and amide group improved the dispersion and interface interaction between MWCNTs and UHMWPE matrix. [ABSTRACT FROM AUTHOR]

Unidirectional fiber‐reinforced composite laminates have limited resistance to out‐of‐plane impact and are prone to structural integrity damage during service due to low‐velocity impact (LVI). In this study, the hot‐press fusion method was employed to repair the impact‐damaged unidirectional carbon fiber‐reinforced poly‐ether‐ether‐ketone (CF/PEEK) thermoplastic composites. No delamination or matrix cracking induced by impact was observed in the repaired specimens, as confirmed by ultrasonic scanning and digital microscope. In addition, the hot pressing treatment enables the fibers to be covered again by the resin matrix, which eliminates fiber pull‐out and fiber/matrix debonding. Afterward, typical responses of CF/PEEK composite laminates to re‐impact and post‐repair compression are presented in a comprehensive and detailed manner, and compared with the initial impact response and compression after impact (CAI) behavior. The effects of three impact energies and two stacking sequences are considered. The results indicate that quasi‐isotropic laminates are more susceptible to localized fracture damage upon re‐impact as the impact energy increases, due to initial fiber breakage, compared to orthotropic laminates. The hot‐press treatment enhances the compression residual strength of the specimen by 20%–30% compared to its state before repair. These studies offer technical insights into the application of the hot‐press fusion method to enhance the mechanical properties of composite laminates post impact damage. [ABSTRACT FROM AUTHOR]

Sealing materials have a wide range of applications in the fields of mechanical power and petrochemicals, they are important basic components for preventing leaks and maintaining the normal operation of equipment. Graphene micronano sheets have become one of the key sealing materials due to their excellent thermal conductivity, corrosion resistance, and mechanical properties. This article mainly uses graphene micro-nano sheets as the main filler, phenolic resin (PF) and polyvinyl butyral (PVB) as binders, combined with tape casting and hot pressing technology, to study the effects of graphene micro-nano sheets content, binder ratio, and hot pressing pressure on the tensile strength, compression rate, and rebound rate of composite sealing gaskets, and explore the hot pressing and laminated object manufacturing process of graphene micro-nano sheets composite sealing gaskets. The results show that when the content of graphene micro-nano sheets is 55%, the PF/PVB mass ratio is 8:15, the molding pressure is 15 MPa, the molding temperature is 120 °C, and the insulation time is 30 min, the graphene micro-nano sheets composite sealing gasket has the best molding processability and property, which can be prepared to meet the quality requirements of graphene micro-nano sheets composite sealing gaskets. [ABSTRACT FROM AUTHOR]

The hot press bend process of the 5A06 aluminum alloy high-stiffener integral panels was studied by FEM simulations and experiments. The high-temperature deformation behaviors and microstructures were tested by the high-temperature uniaxial tensile tests and the electron backscatter diffraction (EBSD), respectively. A set of physically-based constitutive equations and its VUMAT user subroutine, including dislocation density, grain size, and deformation damage, were established. The effects of forming parameters and blank size on the forming quality of the high-stiffener integral panel were studied. The main typical defects were the surface groove, side face curvature and inclination, springback, and wrinkle of the stiffener. The high-stiffener integral panels should be bent above 350 °C and kept for more than 20 min under a pressure of 8 MPa. [ABSTRACT FROM AUTHOR]

In the study, the bonding strength of phenol-formaldehyde (PF) adhesive on plywood under different hot press temperature and time was evaluated. A mechanical mathematical model was established to analyze the curing process of PF adhesive, in which the parameters of model could be used to predict the bonding strength and change rate of plywood. The thermal curing degree of the adhesive was determined by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) as well as Nuclear magnetic resonance (NMR) were used to analyze the chemical structure of adhesives with different curing degree. The results show that higher of hot press temperature, the shorter of time to reach the target temperature. The changed rate constant of bonding strength and the maximum bonding strength of plywood could be calculated by the mechanical mathematical model accurately, and the temperature at 130°C was the optimal temperature for plywood manufacture in the study. FTIR analysis indicated that the primary reaction of PF adhesive in the alkaline medium was the condensation occurring between hydroxymethyl groups and residual active position of other phenolic rings. NMR data presented that the ratio of -CH2- (34.5–35.1 ppm)/CH2-OH (62.4–63.1 ppm) could be used to evaluate the curing degree of PF adhesive. [ABSTRACT FROM AUTHOR]

In this paper, the effect of the laser-ablated pattern designs on the bonding performance of single-lap dissimilar joints between Polyamide 6 (PA6) composite reinforced with 15% short glass fibers (PA6-15GF) and 7075 aluminium (Al) alloy in O-temper condition, manufactured through hot-pressing technique, is studied by tensile-shear testing. From the optical microscopy (OM) and scanning electron microscopy (SEM) observations, it is found that laser ablation can create a favorable surface morphology for the adhesiveless joints. This is proved by obtaining a significant improvement in the lap-shear strength of the treated samples which can be up to 36%. According to the X-ray photoelectron spectroscopy (XPS) results, the surface chemistry is altered by generating an active oxide layer which is a more suitable condition for the PA6-Al direct bonding. Moreover, achieving favourable surface characteristics is shown by the static contact angle (SCA) findings with the acquired increase in surface wettability after the laser ablation. It is observed that the SCA can be decreased from 83 ± 2 (for as-received Al) by approximately more than 65%. The results gained from the experiments demonstrate that the shape of the laser-induced surface pretreatment markedly affects the strength of metal/composite single-lap joints (SLJs). [ABSTRACT FROM AUTHOR]

The solid-state recycling technique has gained significant attention for its ability to reduce metal losses, energy consumption, and solid waste. This study introduced solid-state recycling method to develop zirconia-reinforced AA7075/AA7050 aluminum chip-based matrix composite via a hot press forging process (HPF). The chips were cold-compacted at 35 tons and then hot-forged through a dog bone-shaped die. Full factorial and response surface methodology (RSM) designs were applied using Minitab 18 software. The Face Centred Composite (CCF) of RSM was adopted to rank each factor's effect and analyze interactions between input factors and output responses, followed by process optimization. The selected factors of temperature (Tp) and volume fraction of zirconia (ZrO2) nanoparticles (Vf) were set at 450, 500, and 550 °C with 5, 10, and 15 wt %, respectively. The analyzed responses were ultimate tensile strength (UTS) and microhardness (MH). SEM micrograph revealed a slightly uniform distribution of ZrO2 particles in the matrix. The developed composite gained the maximum strength of 262.52 MPa, a microhardness of 135.5 HV and a density of 2.828 g/cm³ at 550 °C and 10 wt % setting. RSM optimization results suggested 550 °C and 10.15 wt % as optimal conditions for maximum UTS and MH. The preheating temperature exhibited a more significant influence than the ZrO2 volume fraction on the composite's mechanical properties; however, both had a slight effect on grain size. The future prospects of this work are briefly addressed at the end. In conclusion, the HPF process was found to be an efficient recycling method for mitigating environmental impacts by conserving energy and materials. [ABSTRACT FROM AUTHOR]

An isotactic polypropylene/aluminum alloy hybrid was fabricated by a self-made ultrasonic-assisted hot press molding (UAHPM) technology, and the properties and structure at the plastic-metal interface were explored. The surface of aluminum alloy was chemically etched and anodized to form micro- and nano- pore structures. The field emission scanning electron microscopy (FE-SEM) was used to observe the strong micro-nano two-scale mechanical interlocking structures formed at the interface of PP/aluminum hybrid. The element diffusion at the plastic-metal interface was detected by the energy dispersive spectrum. The results showed the stronger isotactic polypropylene/aluminum hybrids were manufactured by the UAHPM technology compared with the traditional press-molded samples. The maximal tensile shear strength of the UAHPMed hybrid reached up to 18.96 MPa, compared with 9.77 MPa for the conventional hybrid. The bonding layer between isotactic polypropylene and the aluminum alloy was 3.7um prepared by the UAHPM technique against 6.2 um for the conventional press molding technology. The thermal property of polypropylene was examined by differential scanning calorimetry (DSC), and crystal structure was characterized by X-ray diffraction (XRD), and the β-crystal of PP existence at the PMH's interface contributes to the excellent plasticity and strong bonding strength. [ABSTRACT FROM AUTHOR]

The current practice in aluminum recycling plants is to change the waste into molten metal through the conventional recycling (CR) manufacturing process. However, the CR technique is so energy-intensive that it also poses an indirect threat to the environment. This paper presents a study on meltless direct recycling hot press forging (DR-HPF) as an alternative sustainable approach that has fewer steps with low energy consumption, as well as preventing the generation of new waste. A laboratory experiment was conducted to study the mechanical properties and surface integrity of AA7075 aluminum alloy by employing a hot press forging (HPF) process under different temperatures (380, 430, and 480 °C) and holding times (0, 60, and 120 min). It was found that as the parameter increased, there was a positive increase in ultimate tensile strength (UTS), elongation to failure (ETF), density, and microhardness. The recycled chips exhibit the best mechanical properties at the highest parameters (480 °C and 120 min), whereas the UTS = 245.62 MPa and ETF = 6.91%, while surface integrity shows that the calculated microhardness and density are 69.02 HV and 2.795 g/cm3, respectively. The UTS result shows that the highest parameters of 480 °C and 120 min are comparable with the Aerospace Specification Metals (ASM) Aluminum AA7075-O standard. This study is a guide for machinists and the manufacturing industry to increase industry sustainability, to preserve the earth for future generations. [ABSTRACT FROM AUTHOR]

Nb-Si based ultrahigh-temperature alloys with the composition of Nb-22Ti-15Si-5Cr-3Al (atomic percentage, at. %) were prepared by hot press sintering (HPS) at 1250, 1350, 1400, 1450 and 1500 °C. The effects of HPS temperatures on the microstructure, room temperature fracture toughness, hardness and isothermal oxidation behavior of the alloys were investigated. The results showed that the microstructures of the alloys prepared by HPS at different temperatures were composed of Nbss, βTiss and γ(Nb,X)5Si3 phases. When the HPS temperature was 1450 °C, the microstructure was fine and nearly equiaxed. When the HPS temperature was lower than 1450 °C, the supersaturated Nbss with insufficient diffusion reaction still existed. When the HPS temperature exceeded 1450 °C, the microstructure coarsened obviously. Both the room temperature fracture toughness and Vickers hardness of the alloys prepared by HPS at 1450 °C were the highest. The alloy prepared by HPS at 1450 °C exhibited the lowest mass gain upon oxidation at 1250 °C for 20 h. The oxide film was mainly composed of Nb2O5, TiNb2O7, TiO2 and a small amount of amorphous silicate. The formation mechanism of oxide film is concluded as follows: TiO2 forms by the preferential reaction of βTiss and O in the alloy; after that, a stable oxide film composed of TiO2 and Nb2O5 forms; then, TiNb2O7 is formed by the reaction of TiO2 and Nb2O5. [ABSTRACT FROM AUTHOR]

Impact by hailstone, volcanic rock, bird strike, or also dropping tools can cause damage to aircraft materials. For maximum safety, the goal is to increase Charpy impact strength (auc) of a carbon-fiber-reinforced thermoplastic polyphenylene sulfide polymer (CFRTP-PPS) composite for potential application to commercial aircraft parts. The layup was three cross-weave CF plies alternating between four PPS plies, [PPS-CF-PPS-CF-PPS-CF-PPS], designated [PPS]4[CF]3. To strengthen, a new process for CFRP-PPS was employed applying homogeneous low voltage electron beam irradiation (HLEBI) to both sides of PPS plies prior to lamination assembly with untreated CF, followed by hot press under 4.0 MPa at 573 K for 8 min. Experimental results showed a 5 kGy HLEBI dose was at or near optimum, increasing auc at each accumulative probability, Pf. Optical microscopy of 5 kGy sample showed a reduction in main crack width with significantly reduced CF separation and pull-out; while, scanning electron microscopy (SEM) and electron dispersive X-ray (EDS) mapping showed PPS adhering to CF. Electron spin resonance (ESR) of a 5 kGy sample indicated lengthening of PPS chains as evidenced by a reduction in dangling bond peak. It Is assumed that 5 kGy HLEBI creates strong bonds at the interface while strengthening the PPS bulk. A model is proposed to illustrate the possible strengthening mechanism. [ABSTRACT FROM AUTHOR]

By regulating preheating time, effects of water/moisture immigration and distribution in wood on sandwich compression formation were investigated in this study. Kiln-dried poplar wood was first immersed in water to result in high moisture content (MC) layers on wood surfaces. These wood specimens were then conditioned at room temperature in sealed plastic bags and preheated with hot press platens at 180 °C to drive water/moisture into wood. Wood preheated for 10–600 s contained one to two high MC layers all the time. Extended preheating time moved the high MC layers from wood surfaces to the center. Mechanical pressure on preheated wood specimens resulted in sandwich compressed wood with the compressed layer(s) position(s) consistent to that of the high MC layer(s) before compression. The positions of compressed layer(s) and MC peak(s) both increased exponentially as a function of the logarithm of preheating time. Wood preheating by platens led to water/moisture migration and therefore controlled water/moisture distribution, thus promoting the softening of specific wood layer(s), which is mainly responsible for sandwich compression. A logarithmical model that can be used for predicting the position(s) of the compressed layer(s) was developed. [ABSTRACT FROM AUTHOR]

Thermoplastic foams allow manufacturing of lightweight parts with good thermal and acoustic insulation properties. To increase the mechanical properties without changing the part weight, these foams can be transformed into structural foams by a newly developed two-step isochoric and isothermal hot press process. Structural foams consist of a low-density foam core and two high-density polymer skins. The production of a polymer skin on the surface of a foam was realized in a hot press process by heating one tool half to process temperatures above glass transition temperature of the amorphous polymer. To manufacture polymer skins on both sides of the foam, it is necessary to turn the foam upside down and repeat the procedure. Structural foams were manufactured with two different polymer foams with different cell structures and densities. Optical analysis of microsections was used to investigate the formation of the polymer skins and the change in foam structure. This study investigates the applicability of an empirical relationship between part densities and bending properties. It was found, that knowledge about the part density alone is not sufficient for the prediction of the bending properties, because the foam structure (e.g. open or closed foam cells) has a considerable impact on the foam properties. [ABSTRACT FROM AUTHOR]

This study was carried out to improve the surface of the AA7075 alloy, which does not resist wear. Therefore Al–SiC composite layer on the surface of AA 7075 material was coated with Al+5vol.%SiC powders under 600°C and 100, 120, 140 MPa pressure by the hot pressing sintering method. The microstructure of the transition zone between the coating and the substrate material was analyzed by using optical microscopy (OM), energy dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) techniques. In addition, XRD measurement and microhardness of the coating layer were obtained. Coating surface was also subject to linear reciprocating wear test and coefficient of friction (COF), wear volume, and mass loss were detected. The results have shown that micro-pores between Al and SiC powders reduced by increasing the pressing pressure. However, although there was a reduction in wear volume and mass loss, microhardness values dramatically increased. Wear test was modeled in ANSYS 2021 R2 package program depending on Archard's law and numerical analysis was conducted. As a result of the experimental results and numerical analysis, the volume loss values occurring in the coating area were found to be compatible with each other. [ABSTRACT FROM AUTHOR]

Poly (styrene-4-vinylbenzyl chloride) (PSVBC) was synthesized by polymerization of 4-vinylbenzyl chloride and styrene. FTIR was used for characterization of PSVBC and for curing of three protein/PSVBC adhesives (proteins include potato, corn, and pea proteins). Protein-PSVBC adhesives were investigated for bonding maple veneers. The shear strength and water resistance of the resultant maple laminates were evaluated. More specifically, the effects of the NaOH concentration, hot press conditions (temperature and time), total solids content, and protein-PSVBC weight ratios on the shear strengths and water resistance were studied. The addition of PSVBC improved the wet shear strength of the laminates from 0.1 to 0.85 MPa for potato-PSVBC adhesive and from 0.1 to 0.73 MPa for corn-PSVBC adhesive. However, the addition of PSVBC did not increase the wet strength of the laminates for the pea-PSVBC adhesive. [ABSTRACT FROM AUTHOR]

Herein, an investigation on the influence of the hot press forming (HPF) temperature cycles of a medium manganese, high ductility, zinc‐coated steel with ≈1000 MPa final tensile strength (HPF1000‐GI), with a specific emphasis on the risks of liquid metal embrittlement (LME) induced cracking during resistance spot welding (RSW) is presented. The HPF1000‐GI steel is hot press formed using several temperature cycles, and subsequently the LME sensitivity of the variously hot press formed materials are investigated using both dedicated RSW experiments as well as high‐temperature tensile testing. It is shown that the LME sensitivity of the HPF1000‐GI steel is significantly reduced after hot forming at higher intercritical temperatures, and that this favorable behavior is caused by microstructural changes at the coating‐substrate interface. [ABSTRACT FROM AUTHOR]

This research investigates the performance of medium density fiberboard (MDF) with respect to hot press parameters. The performance of the board, type of glue, and production efficiency determine the optimum temperature and pressure for hot pressing. The actual temperature of the hot press inside the MDF board determines the properties of the final product. Hence, the optimal hot press parameters for the desired product are experimentally obtained. Moreover, MDF is experimentally investigated in terms of its vertical density profile, bending, and internal bonding under the various input parameters of temperature, pressure, cycle time, and moisture content during the manufacturing process. The experimental study is carried out by varying the temperature, pressure, cycle time, and moisture content in the ranges of 200–220 °C, 145–155 bar, 260–275 s, and 8–10%, respectively. Consequently, the optimum input parameters of a hot-pressing temperature of 220 °C, pressure of 155 bar, cycle time of 256 s, and moisture content of 8% are identified for the required internal bonding (0.64 N/ mm 2 ), bending (32 N/ mm 2 ), and increase in both the core and peak density of the vertical density profile as per the ASTM standard. [ABSTRACT FROM AUTHOR]

High-strength hot-press-forming (HPF) steel is extensively utilized in the automotive industry to lower the weights of car bodies. Resistance spot welding is commonly used when assembling car bodies; however, laser overlap welding is gradually replacing resistance spot welding owing to its high productivity and quality. The joint strength of laser overlap-welded HPF steel with a tensile strength of 2.0 GPa was investigated in the present study. Laser wobble welding was employed to increase the interface-bead width and the resultant joint strength. In laser overlap welding without wobbling, all the specimens were fractured at the interface during the tensile-shear test where the maximum load was 8.2 kN. An increase in the wobbling width not only induced an increase in the interface-bead width but also splitting of the weld bead. The interface-bead width (6.7 mm) was much higher than the base metal thickness (1.2 mm), with a wobble width of 1.6 mm. The wide interface-bead width resulted in a fracture load of 10.7 kN, and the fracture location moved from the interface to the upper plate. Laser wobble welding was confirmed to be an effective approach for increasing the joint strength in laser overlap welding. [ABSTRACT FROM AUTHOR]

Scheduling heat treatment jobs in a hot press forging factory involves forming batches of multiple workpieces for the given furnaces, determining the start time of heating each batch, and sorting out the order of cooling the heated workpieces. Among these, forming batches is particularly difficult because of the various constraints that must be satisfied. This paper proposes an optimization method based on an evolutionary algorithm to search for a heat treatment schedule of maximum productivity with minimum energy cost, satisfying various constraints imposed on the batches. Our method encodes a candidate solution as a permutation of heat treatment jobs and decodes it such that the jobs are grouped into batches satisfying all constraints. Each candidate schedule is evaluated by simulating the heating and cooling processes using cost models for processing time and energy consumption, which are learned from historical process data. Simulation experiments reveal that the schedules built using the proposed method achieve higher productivity with lower energy costs than those built by human experts. [ABSTRACT FROM AUTHOR]

In this study, a novel high entropy alloy from the Al-Cr-Fe-Mn-Mo family was successfully prepared by mechanical alloying followed by hot press sintering. The samples were investigated by x-ray diffraction, electron backscatter diffraction, and scanning and transmission electron microscopy. The sintered samples consist of a unique new multielement body-centered cubic solid solution (more than 98 vol.%). Moreover, it is shown that, by controlling the processing conditions, it is possible to limit the formation of carbides and oxides, which are common when using powder metallurgy processing routes. The mechanical properties were investigated by micro-indentation and compression tests from room temperature up to 800°C. The results showed high micro-hardness up to 950 HV1N. The hot compression results revealed promising mechanical properties, especially at high temperatures, e.g., at 600°C, the yield strength was 1022 MPa, the maximum compressive stress was 1327 MPa, and the strain at failure was 21.8%. [ABSTRACT FROM AUTHOR]

In recent years, significant research has been carried out for a long time on improving the mechanical properties of the surfaces of metallic materials with various surface coating methods. This study was conducted to investigate in detail the microstructure and wear behaviour properties of the coating, made by the hot press sintering method (HPSM), on AlZn5.5MgCu alloy. The coating layer was hot pressed for 25 min with Al+5%vol. SiC powder particles at sintering temperatures of 580, 600, and 620°C under 120 MPa pressure. The microstructure of the coating produced at different sintering temperatures and the microstructures of the interface region and the substrate were analysed by optical microscopy (OM), Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM-EDS), and X-ray diffraction (XRD). Microhardness values were also measured on the coating layer and the linear reciprocating wear test was applied. The microstructure results indicated a homogeneous distribution of SiC particles in the Al powder. Also, the mass loss reduced and the microhardness values significantly raised due to the increase in sintering temperature values. It was seen that with this method, the coating thickness amount could be made in accordance with the desired value. [ABSTRACT FROM AUTHOR]

The widespread use of synthetic composite materials has raised environmental concerns due to their non-biodegradability and energy-intensive production. This paper explores the potential of natural composites, specifically flax–polypropylene, as a sustainable alternative to traditional composites for semi-structural applications. In fact, the mechanical properties of flax–polypropylene composites are similar to synthetic ones (such as those made with E-glass fibers). However, processing challenges related to fiber–matrix interaction and material degradation necessitate suited process parameters for this sustainable type of material. For this reason, this review highlights the importance of optimizing existing manufacturing processes, such as hot press molding, to better accommodate the specific characteristics of polypropylene–flax composites. By refining the parameters and techniques involved in hot press molding, researchers should overcome current limitations and fully capitalize on its potential to produce composite materials of optimal quality. Therefore, a comprehensive literature assessment was conducted to analyze the properties and processing challenges of flax–polypropylene composites. Key process parameters affecting the material's performance are identified and discussed. By optimizing process parameters for flax–polypropylene composites, it is possible to develop a sustainable and high-performance material with a reduced environmental footprint. Further research is needed to scale up production and explore different applications for this sustainable composite material. [ABSTRACT FROM AUTHOR]

The bending angle at the peak load is regarded as the most important parameter for evaluating bending properties of hot-press-forming (HPF) steels. However, it is not a mechanics-based parameter for the bending criterion, and the data interpretation is difficult because bending criteria in relation with microstructures and associated bending mechanisms have not been verified yet. In this study, effects of coating and baking treatments on bending angles at the peak load of three kinds of 1470 MPa-grade HPF steels were investigated by interrupted three-point bending tests coupled with direct microstructural observation. According to direct observations of sequential cracking processes of V-shaped crack (V-crack), bending procedures were classified into four stages: (1) formation of small V-crack, (2) increase in number and size of V-cracks, (3) initiation of shear-crack propagation from the V-crack tip, and (4) further propagation and opening of the shear crack. The minimum bending angle required for initiating the shear-crack propagation from the V-crack tip was defined as a critical angle, which meant the boundary between the 2nd and 3rd stages. The present bending behavior related with critical bending angle and V-cracking could be interpreted similarly by the fracture-mechanics concept, i.e., the initiation of shear-crack propagation. [ABSTRACT FROM AUTHOR]

The production of magnesium alloys by the powder metallurgy (P/M) method is difficult and troublesome. An alternative production method with easy usability is therefore required, and the properties of new Mg alloys should be examined after production. A type of P/M method (the hot press method) can be applied to produce new Mg alloys with superior properties. In this study, the effect of Al addition and the use of the hot press method on the microstructure and mechanical properties of magnesium alloy were investigated. TZA series magnesium alloys (Mg5Sn4Zn-xAl) were developed, and these alloys were produced in this way for the first time. The paraffin coating technique was applied to prevent the risk of ignition or oxidation of the Mg powders during the mixing process. The experimental results showed that new non-porous Mg alloys with a relative density above 99% were successfully produced using the hot press method. Intermetallic phases were homogeneously distributed at the grain boundaries due to the use of the hot press process. The amount of Mg17Al12 phase in the microstructure increased with the addition of more Al, and this improved the mechanical properties. TZA544 magnesium alloy exhibits mechanical properties that are superior to those of many magnesium alloys in current use. [ABSTRACT FROM AUTHOR]

A new 3D printer equipped novel nozzle structure for continuous carbon fiber-reinforced thermoplastics (C-CFRTP) was developed and the suitable printing conditions were studied. C-CFRTP filament and additional matrix resin were supplied independently using each extruder, which is useful for variety printing and precise form control in 3D printing. To measure the mechanical properties, specimens for tensile strength testing were fabricated using C-CFRTP filament (Vf:50%) without additional matrix resin. The experimental results indicate that the tensile strength and Young’s modulus were approximately 700 MPa and 53 GPa, respectively. The recrystallization effect through annealing after 3D printing yielded no drastic improvement. The mechanical properties were considerably improved by a hot-press treatment after 3D printing. The tensile strength and Young’s modulus increased to approximately 1400 MPa and approximately 90 GPa, respectively. These results suggest that one of the useful applications of C-CFRTP 3D printing technology is preforming of small parts in industrial products. [ABSTRACT FROM AUTHOR]

This paper mainly concerns the thermo-mechanical analysis to evaluate the process parameters in the hot press forming with the 22MnB5 sheet such as the austenitization temperature, transport and quenching time for enhancing the efficiency in the production cycle. It is noted that the transport time is most influencing process parameter in the hot press forming to increase production efficiency without sacrificing the strength of the final product. In addition, we newly proposed a scheme to reproduce the flow curves of the hot stamped 22MnB5 sheet with respect to the martensite fraction by correlating the numerical analyses and tensile test results. To take into consideration of the strength variation in the hot stamped door impact beam, entire part is partitioned into several domains on which adaptive flow curves are assigned with respect to the martensite fraction. It demonstrates a good agreement with experimental 3-point bending test with the hot stamped door impact beam when applying the proposed method adopting adaptive flow curves with respect to the martensite fraction. [ABSTRACT FROM AUTHOR]

The present article focused on the residual strains and deformation of the laminates fabricated by rapid hot press process using prepreg. Strain gauges and laser tracker were utilized to measure the residual strains and deformation of the laminates. By studying the effects of curing time and de-molding temperature on residual strains and deformation of composite laminates, the efficient curing conditions were proposed and good processing quality was ensured. The results indicate that the laminates with low curing degree incline to generate high residual stresses during curing and cooling processes. The effects of cure duration and de-molding temperature on the deformation degree and type of laminates are significant. In order to ensure both curing efficiency and low deformation, the curing time of the resin and de-molding temperature should be designed cautiously. The experimental results suggest that the curing duration longer than 12 min is needed, and the de-molding temperature should be no less than 40°C lower than glass transition temperature of the cured matrix. [ABSTRACT FROM AUTHOR]

Trapped-flux magnets made of stacks of superconducting tapes are an interesting and important alternative to the application of rare-earth permanent magnets and trapping flux in bulk superconductors. Many applications, such as electric motors, can require the complex shapes of magnetic elements to combat issues such as demagnetization during the operation. Therefore, a reliable production technique of high temperature superconductor (HTS) stacks with different geometries is required to meet the needs of industry. In this article, a method of shaping the epoxy-glued stacks of superconducting tapes is proposed and investigated. The application of hot press allows to easily change the shape of the stack. The influence of shaping the stack on the density of trapped magnetic flux as well as critical current are presented. Experimental and numerical analyses are performed and their results are matched to find the change in the superconducting properties of the tapes. They show that with the proper process parameters the stacks can be shaped with only minor decrease of performance. However, strong degradation is observed if the applied force is too high. The observed problems are discussed and the possible solutions are proposed. [ABSTRACT FROM AUTHOR]

Nowadays, composite sandwich tubes are extensively utilized in the civil and aerospace industries due to their superior strength-to-weight mechanical properties. Origami-based core offers a large enhancement of the mechanical properties, yet little study research focuses on the effect of various foldcore configurations on the transverse mechanical properties of sandwich tubes, necessitating the design method for applications. This study introduces an innovative approach by incorporating origami into the composite sandwich core to enhance the transverse energy absorption capacity. The quasi-static transverse mechanical properties of carbon fibre-reinforced polymer (CFRP) sandwich tubes with foldcores are studied under three-point bending-like local compression and transverse structural compression. A systematic geometric design framework and numerical modelling technique are provided. By integrating finite element analysis and experiments, the research investigates the effects of various origami foldcore configurations and geometric parameters on transverse energy absorption capacity. The experiment setup is provided by sandwich tubular specimens with a full-diamond configuration as the foldcore. The cylindrical tubes (foldcore) of the sandwich structures were manufactured using four plies [0°]4 of T700 (T300) woven CFRP with the hot press moulding (vacuum bag using female and male moulds) technique respectively. Then, the parametric study and damage mode analysis of eight different foldcore patterns (axial Miura, circumferential Miura, diamond, Kresling, and their curved-creased counterparts) were studied. The results showed the superior energy absorption performance of the sandwich tube with Miura-pattern foldcore over the origami-pattern counterparts, nested tube, and traditional honeycomb sandwich tube with CFRP or aluminium-made cores. Therefore, the structural parameters optimisation of the Miura pattern tube was carried out by the Response Surface method (RSM) and a design strategy for increasing the energy absorption capacity was found. The findings offer guidance for designing high-specific energy absorption tubular structures for future advanced engineering applications. [ABSTRACT FROM AUTHOR]

The microstructures and properties of powder metallurgy Ti-45Al-10Nb (at.%) alloys fabricated by vacuum hot pressing consolidation of milled powder have been investigated. Under the sintering conditions, the alloy exhibits much fine-grained microstructure, which consists of a double phase γ + α2 microstructure containing Ti2AlC precipitates. Tensile properties are measured at 900 °C–1000 °C under a strain rate of 1 × 10−4 s−1. This alloy displayed outstanding high-temperature tensile strength, with tensile strength (UTS) 410.2 MPa and elongation (ε) 12.5% at 900 °C, and UTS 189 MPa and ε 16.7% at 1000 °C, respectively. [ABSTRACT FROM AUTHOR]

Bulk Al/4wt-%AlO nanocomposites were prepared by consolidating nanocomposite powders using pressureless microwave sintering, microwave-assisted hot press sintering and conventional hot pressing techniques. Microstructural observations revealed that the microwave- assisted hot press sintering at different sintering temperatures of 400°C and 500°C resulted in more densification and smaller grain size for Al/AlO nanocomposite as compared with the conventional hot pressing. Moreover, the application of pressure in microwave sintering process led to more densification and grain growth. Mechanical properties resulting from microhardness and nanoindentation tests were also compared between three-method processed samples. It was found that the microwave-assisted hot-pressed sample exhibited higher hardness and elastic modulus in comparison with microwave-sintered and conventional hot-pressed samples. The improvement in the mechanical properties can be ascribed to lower porosity of microwave-assisted hot-pressed sample. [ABSTRACT FROM AUTHOR]

Waste newspapers (WNPs), composed of mostly wood fibers and small amounts of inorganic fillers and printing ink, are a low-cost, abundant, and readily available form of household waste. Urea formaldehyde (UF) resin is used routinely to produce wood-based panel boards even though it releases harmful formaldehyde. The best way of resolving this issue is to use formaldehyde-free adhesives from renewable resources. Kraft lignin, a readily available, low-cost, and renewable waste product from the pulping industry, is used mainly as a fuel. Kraft lignin has good bonding ability to wood-based panel boards and improves water resistance. In this research, fiberboards were produced using a dry-processing method from recycled WNPs and bonded with kraft lignin instead of UF. The physical and mechanical properties of the produced fiberboards were evaluated. The results showed that the hot press temperature and kraft lignin content remarkably influenced the physical and mechanical properties of the fiberboards. As the hot press temperature and kraft lignin content increased, the overall performance of the fiberboards improved accordingly. The results indicate that WNPs could be a potential sustainable resource for fiberboards production. [ABSTRACT FROM AUTHOR]

A hot-press tackifying process was used to improve the mechanical properties of cured laminates in vacuum-assisted resin transfer molding by placing a thermoplastic film into the preforms at various pressures and temperatures. Three modified preforms were prepared at 0.1, 0.3, and 0.6 MPa using an autoclave, and the laminates were then produced via vacuum-assisted resin transfer molding. The mechanical properties of the modified laminates were tested and compared to those of the unmodified ones. The fiber volume fractions of the modified laminates decreased with increasing pressure. The tensile strength of the modified laminates at the three pressures improved by 16.78%, 41.21%, and 29.47%, respectively, compared to the unmodified samples. Modified laminates at 0.3 MPa showed better results than those at 0.1 and 0.6 MPa, which were all better than the unmodified samples. The modulus of the modified laminates from vacuum-assisted resin transfer molding was improved by 2.48%, 19.01%, and 13.22%, respectively. The effect of the hot-press tackifying in improving the tensile strength and modulus of a laminate on a pre-impregnated laminate (prepreg) using the autoclave was studied and compared to that of the unmodified case. Here, the tensile strength increased by 32.5% and 12.3%, respectively. [ABSTRACT FROM AUTHOR]

Meltless recycling technique has been utilized to overcome the lack of primary resources, focusing on reducing the usage of energy and materials. Hot press was proposed as a novel direct recycling technique which results in astoundingly low energy usage in contrast with conventional recycling. The aim of this study is to prove the technical feasibility of this approach by characterizing the recycled samples. For this purpose, AA6061 aluminium chips were recycled by utilizing hot press process under various operating temperature (Ts = 430, 480, and 530 °C) and holding times (ts = 60, 90, and 120 min). The maximum mechanical properties of recycled chip are Ultimate tensile strength (UTS) = 266.78 MPa, Elongation to failure (ETF) = 16.129%, while, for surface integrity of the chips, the calculated microhardness is 81.744 HV, exhibited at Ts = 530 °C and ts = 120 min. It is comparable to theoretical AA6061 T4-temper where maximum UTS and microhardness is increased up to 9.27% and 20.48%, respectively. As the desired mechanical properties of forgings can only be obtained by means of a final heat treatment, T5-temper, aging after forging process was employed. Heat treated recycled billet AA6061 (T5-temper) are considered comparable with as-received AA6061 T6, where the value of microhardness (98.649 HV) at 175 °C and 120 min of aging condition was revealed to be greater than 3.18%. Although it is quite early to put a base mainly on the observations in experimental settings, the potential for significant improvement offered by the direct recycling methods for production aluminium scrap can be clearly demonstrated. This overtures perspectives for industrial development of solid state recycling processes as environmentally benign alternatives of current melting based practices. [ABSTRACT FROM AUTHOR]

Hydrothermally synthesized ZnS nanopowders comprising small and large particles were used to synthesize ZnS ceramics. Small particles (200 nm) existed in the gaps between the large particles (0.7 μm) and assisted the densification of the ZnS ceramics. ZnS ceramics sintered at low temperatures (<1000°C) exhibited small grains with large grain‐boundary areas that provided diffusion paths for carbon ions from the graphite mold, resulting in carbonate absorption bands. ZnS ceramics sintered at high temperatures (≥1000°C) for a long time (≥2.0 hours) exhibited a dense microstructure with very large grains (>500 μm). The ZnS liquid phase, which was formed at approximately 980°C, assisted the densification and grain growth of the ZnS ceramics. A 3.0‐mm‐thick ZnS ceramic sintered at 1000°C for 16 hours showed a high Knoop hardness (321 kgf/mm2) and a high transmittance of 71% in the wavelength range 6.0‐12 μm without carbonate absorption bands. [ABSTRACT FROM AUTHOR]